In view of the problems of inaccurate localization and ambiguous orientation of traditional cross power spectrum(CS) in direction of arrival estimation, an improved algorithm of sound source localization using a circular microphone array is proposed and demonstrated by practical experiments. In the proposed algorithm, the twelve-element circular microphone array is firstly designed, then the phase rotation factor is defined by combining the time delay with the phase information of speech signals received by each pair of microphone and introduced into the traditional cross power spectrum to define novel circular integrated cross power spectrum(CICS), finally the sound source orientation can be estimated by CICS algorithm. The simulation and practical experiment results show that the proposed algorithm can greatly improve the estimated accuracy of source orientation compared with the traditional cross spectrum algorithm.